In study of reduced physical activity in adults with prediabetes, just two weeks of inactivity found to cause impaired glycemic control; may progress patients to type 2 diabetes
It has long been accepted that diet and exercise are critical to maintaining glycemic control and preventing complications associated with both prediabetes and diabetes. For older adults who find themselves unable to engage in physical activity, however, what are the consequences of a sedentary lifestyle?
Researchers out of Ontario, Canada set out to answer this question in a five-week trial that followed senior adults with prediabetes. While a few other studies have sought to assess the effects of inactivity on glycemic control, this may be the first study that examined the effects of inactivity on not only metabolic function, but also the restoration of glycemic control following remobilization.
Twenty-two adults with excess weight (12 men, 10 women) ages 69 ± 4 years with prediabetes participated in the study. Eligibility was met if the participants had a fasting glucose of <126 mg/dL and had not been diagnosed with diabetes, were non-smoking individuals, and had not been diagnosed with any chronic illness.
Participants were monitored for baseline glucose, body composition, and muscle biopsy levels on day one, and then underwent seven days of “normal” physical activity (step count 7362 ± 3294). Following the weeklong period of physical activity, participants then were placed on a step reduction period for 14 days, maintaining <1000 steps per day. The final 14 days consisted of the re-initiation of activity (step count 7117 ± 3819), with all laboratory levels repeated following each cycle of activity change.
All data was analyzed for significance using Tukey’s post hoc test, with p<0.05 considered statistically significant.
Following completion of the study, investigators found that following the two-week period of reduction in activity, average blood glucose levels had significantly increased from baseline (p<0.01) and never fully recovered back to baseline after the final two-week period of re-initiation of activity, though this recovery measure was not statistically significant. Additionally, patients’ insulin sensitivity index was decreased (3.9 ± 0.7 to 2.9 ± 0.4, P < 0.05) and insulin resistance was increased. Both of these latter two insulin values were altered from baseline and neither showed a return during the recovery period.
Investigators also examined muscle protein synthesis (MPS) and found that rates of MPS had significantly reduced from baseline but returned during the recovery period. Body composition did not change significantly from baseline throughout the 5-week study duration.
As of 2017, the CDC estimates that over 84 million people in the United States alone are living with prediabetes and that nearly ¼ of all people age 65 and older have been diagnosed with full blown diabetes. As patients age and physical activity declines, the implications of a sedentary lifestyle are now increasingly something to worry about, especially in the diabetes community.
Overall, the results from this study are profound, showing that an abrupt cessation of physical activity can be detrimental to not only glycemic control in patients with prediabetes, but can put patients at significant risk for progression to type 2 diabetes even when activity is restored. As the number of older adults living with prediabetes continues to rise, the importance of maintaining a level of habitual activity must be stressed.
- Acute periods of significantly reduced physical activity can lead to impaired glycemic control and an inability to restore glycemic levels upon re-initiation of activity.
- A decrease in insulin sensitivity and an increase in insulin resistance can occur during acute periods of inactivity and never fully restore to baseline.
- Older adults with prediabetes are at significant risk for progression to type 2 diabetes when physical activity is reduced and should be placed on scheduled activity to reduce this risk.
McGlory, C et al. (2018) Failed Recovery of Glycemic Control and Myofibrillar Protein Synthesis With 2 wk of Physical Inactivity in Overweight, Prediabetic Older Adults, The Journals of Gerontology: Series A. 73(8) 1070–1077, https://doi.org/10.1093/gerona/glx203
Clarke Powell, Pharm.D. Candidate 2019, LECOM School of Pharmacy